Portable sink



FIG. 1 is a perspective, right side and front view showing my design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a front elevational view thereof; and,

FIG. 4 is a top plan view thereof.

The rear and bottom views of a portable sink are not being claimed in the present design. 

The ornamental design for a portable sink, as shown and described. 